There has been known a shock-absorbing base frame of a pump assembly (RU Patent 103584, IPC F04D29/00, publ. Apr. 20, 2011, the patent owner—OOO “NKMZ”), comprising self-correcting adjustable mounting means (or in more correct terminology—mounting supports). However, as it describes a base frame of pump assembly rather than the electrical pump assembly as a whole, comprising a single-stage double-volute centrifugal pump, an electric drive motor, the shafts of which are coupled by a coupling, and a base (or mounting) frame having supports mounted under the feet of a pump and/or a motor, a number of features of the interaction of all of the major components of the assembly were not considered.
There has been known a centrifugal electric pump assembly, comprising a pump and a motor mounted on a common foundation base and coupled by a coupling (RU Patent 95043, IPC F04D1/00, F16D3/50, publ. Jun. 10, 2010). It is argued that the technical effect is to reduce wear of bearings, motor overheating, noise and vibration.
However, this assembly relates to the nuclear industry, and therefore does not take into account the characteristics of mainline electric oil pump assemblies. Furthermore, this patent 2.5 focuses on the specific problem of improving the design of a flexible coupling between the pump and motor shafts. A flexible coupling for centrifugal pump unit has been specifically described in RU Patent 2246047 (IPC F04D29/62, publ. Feb. 10, 2005), however, the disadvantages of this coupling include relatively low operational reliability, ageing and thermal ageing of rubber flexible elements with change of the elasticity coefficient of rubber under large variations in temperature, especially in the presence of oil vapours and possible contact with oil when using the coupling in mainline centrifugal oil pump.
As for the pump being the most important and challenging component of the mainline electric oil pump assembly, there has been known a double-volute centrifugal pump for pumping oil of JSC Sumskoy plant “Nasosenergomash” (Patent of Ukraine 22403, IPC F04D 1/00, publ. Apr. 24, 2007). The pump comprises a housing within which the rotor is mounted, on whose shaft bearings, mechanical seals and an impeller, which together with the inlet volume and expanding volute of the housing constituting a flow area are fixed. The housing is further installed with a circulation system of lubrication and cooling of inner cavity of mechanical seals, and the impeller mounted to a shaft is split in two halves. The presence of the two halves of the impeller enables to double reduce the vibration characteristics of the pump by mounting the halves of the impeller to the shaft of the rotor with the rotation of one half relative to the other about the axis of the rotor on the half angle between the blades. Rotation of the halves is provided by a suitable arrangement of the key grooves. A disadvantage of this pump is presence of keys and key grooves, which weaken the shaft of the rotor and are being stress concentrators, given the fundamental presence of the backlashes in keyed connections, the presence of key grooves on the shaft facilitating excitation of vibrations of the pump rotor.
There has been also known almost the same double-volute centrifugal pump for pumping oil of the same patent holder—JSC Sumskoy plant “Nasosenergomash” (together with JSC “VNIIAEN” (Sumy, Ukraine)) (RU Patent 106680, IPC F04D1/00, F04D29/00, publ. Jul. 20, 2011). The disadvantage of this pump are gaps in the bearing sliding supports that causes dynamic beats in the gaps that contribute to increased vibration and noise of the pump.
Regarding the analogue method for assembling the frame-mounted pump assembly by means of its high-efficiency assembly, casting, machining and polishing (or grinding) there has been known a published international PCT application WO2010030802 (IPC F04D 17/02, publ. Mar. 18, 2010) for a method of assembly of a high-efficiency three-stage horizontal centrifugal pump as a part of an electric pump assembly. However, this method is still not designed for the assembly of the mainline electric oil pump assembly and therefore does not take into account many of design features of such assembly.
Also there has been known a method of manufacturing a horizontal pedestal-mounted (analogue of a base frame) pump assembly described in UK Patent 1255169 (IPC F04C19/00, publ. Dec. 1, 1971) using machining of several pump surfaces for subsequent critical connections during a single set-up. However, the described pump is not a mainline oil pump type and therefore this method of manufacturing is not designed for the assembly of the mainline electric oil pump assembly and therefore does not take into account many of the design features of such assembly.
As an analogue of method for high-efficiency frame-mounted assembling has been known a method for assembling a horizontally oriented turbo compressor unit (RU Patent 2263247, IPC F16M5/00, F16M9/00, F01D25/28, publ. Oct. 27, 2005), consisting of a turbo compressor group (functional analogue of a pump) and a charger (a functional analogue of a motor), and their frames (mounting and transport and technological ones) with support surfaces.
The disadvantages of this method include the use of complex and time-consuming methods of assembling and installation of the unit on the frames and the use of spacer shims (or plates with measured thickness) with a number of important limitations to use.